Increasingly alarmed by the inability of Congress to pass a spending bill or avoid sequestration, the military service chiefs are providing more details about what will happen if lawmakers don’t take action.

For the U.S. Navy, the rising crescendo of warnings now hits at the heart of the fleet’s activities — the deployed carrier strike groups (CSGs) and amphibious ready groups (ARGs) that project naval power around the world, and that underpin U.S. military activities in the Middle East and the Pacific.

Should sequestration strike after March 1, warns Adm. Jonathan Greenert, chief of naval operations, the fleet will be forced to stop “nearly all non-deployed operations,” a move “which will ultimately prevent CSGs and ARGs from deploying.”

Operations in the Middle East and Pacific regions will be further reduced, Greenert said, and while training will continue for the next two carrier groups to deploy this year, starting in October “we will likely not have trained replacements for our deployed units.”

“Once we shut down our sustainment training it will take our ships and squadrons about nine months to conduct the maintenance and training needed to be certified to deploy again,” Greenert said.

The stark warnings came in an internal message sent Jan. 24 by Greenert to Navy flag officers and senior executives. A copy of the message was obtained by Defense News.

Greenert provided more details about a number of cost-cutting moves the Navy is making and could make, a follow-up to messages earlier this month from Navy Secretary Ray Mabus and Greenert and his fellow service chiefs.

Those missives to Congress and the fleet noted that a year-long continuing resolution (CR) will leave the Navy with a $4.6 billion shortfall in operations and maintenance (OMN) requirements for the remainder of fiscal 2013.

Should sequestration hit on March 1, Mabus said on Jan. 17, the service would need to find another $4.6 billion in OMN funds, in addition to the $4.6 billion year-long CR shortfall.

Service chiefs have stressed that personnel pay and benefits are protected from the current budget crisis, but just about anything else is open to cuts.

In the face of a threatened year-long CR, Greenert said that, “starting now,” a number of moves are being made. They include:

 Overhauls to about 30 of the fleet’s 187 surface ships will be cancelled. The work affects most of the overhauls to be done at commercial shipyards between April and September.

 While overhauls will continue at the four Navy-owned “public shipyards,” nearly 10 percent of the government shipyard workforce — more than 3,000 employees — will be reduced through termination of temporary employees and implementing a civilian hiring freeze.

 Depot-level maintenance on about 250 aircraft scheduled between April and September could be cancelled.

 Spending on base operating support is being reduced, and service officials are advised to plan to cancel repair and modernization of nearly all piers, runways and buildings through September.

 Information technology support is being cut, non-mission-essential conferences are cancelled, and travel will be severely limited.

The reductions are intended to be reversible, Greenert said, and will continue until a spending bill is passed or Congress reprograms money into the OMN accounts.

“But some of these things, you can defer it, but you can’t reverse it,” said a Navy official.

“We’re just climbing out of a period of reduced funding, and the path ahead was beginning to look positive,” the official said, referring to improved maintenance accounts.

“But without that expected spending bill … everybody’s got to plan, but you can’t do it if you don’t have the money.”

The full text of Greenert’s message:

Subject: Navy's Budget Situation

Admirals and Senior Executives,

As part of my regular updates to you, I wanted to keep you informed of Navy's budget situation. We have budget shortfalls today because we are funded under a Continuing Resolution (CR) and may have significant additional budget reductions starting in March because of sequestration. My most immediate concern is to our Operation & Maintenance (OMN) account.

We are operating today with a reduced budget because the CR funds us at FY12 base budget levels. These levels are inadequate for our needs in FY13, falling $3.2B short of our planned OMN budget. Due to another $1.4B of unplanned growth, operating under a CR for the entire fiscal year leaves us about $4.6 billion below our OMN requirements in FY13.

Additionally, the CR provides only limited ability to transfer funds from investment accounts to OMN to cover our shortfalls. Because of this, we need to cut back on ops and maintenance to get our spending rate down where it needs to be to remain within the controls of a yearlong CR.

We are making the following reductions, starting now, to ensure we can fund ongoing deployments and other mission-critical activities.

These reductions are intended to be reversible and will continue until a spending bill is passed or we receive authority from Congress to reprogram money from investment accounts into operations and maintenance:

 Plan to cancel the majority of surface ship maintenance availabilities at private shipyards between April and September. This will affect about 30 of our 187 surface ships. We will preserve most availabilities at our public shipyards, but expect throughput to be reduced due to civilian personnel actions that are discussed below.

 Plan to cancel all aircraft depot maintenance from April to September, affecting about 250 aircraft.

 Reduce spending on base operating support and plan to cancel repair and modernization of nearly all piers, runways, buildings and other facilities through Sep 2013.

 Terminate temporary employees and implement a civilian hiring freeze. This will reduce our shipyard workforce by more than 3,000 — almost 10 percent of the workforce (mostly in shipyards and base operating support).

These steps come at a price. Much like putting off an oil change because you can't afford the $20 service, we save in the short term, but shorten the car's life and add to the backlog of work for later.

If sequestration comes on March 1, we will have an additional $4B OMN reduction for FY13. This will require more aggressive actions unless we gain authority to move investment funds into OMN. These actions include:

 Stop nearly all non-deployed operations for training and exercises, which will ultimately prevent CSGs and ARGs from deploying.

 Further reduce deployed operations in the Middle East and Pacific.

 We will retain some CSG training for late FY13 deployers (Nimitz and George H.W. Bush CSGs), but in FY14 we will likely not have trained replacements for our deployed units.

Our fleet commanders are studying this issue closely, and we will preserve as much maintenance and training as possible throughout FY13 and into FY14. However, once we shut down our sustainment training it will take our ships and squadrons about 9 months to conduct the maintenance and training needed to be certified to deploy again.

I appreciate your continued support on this pressing issue and I will continue to keep you informed. If you have questions, don't hesitate to ask.